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NASA SLS/Orion/Payloads

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6 hours ago, RCgothic said:

There's no reason why there couldn't be a reserve for a deorbit burn once payload insertion is complete.

rs-25 doesnt restart, and even if it did, it would need ullage thrusters to do so, adding another layer of complexity

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7 minutes ago, insert_name said:

rs-25 doesnt restart, and even if it did, it would need ullage thrusters to do so, adding another layer of complexity

I was thinking the same thing but didn’t feel I should say so good on you.

One thing I wanted to say was that the RS-25s have a relatively high throttle margin when it comes to their minimum, and since they can’t shut up, when trying to turn them around to face retrograde, you’d skew your orbit as you burned eccentrically or normally depending on your path to the opposing path. So it wouldn’t work.

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Liquids make more sense. Solid rockets are fireworks.

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1 minute ago, tater said:

Liquids make more sense. Solid rockets are fireworks.

both shoot stuff out the back to make things go the other directions. I don't see how liquid fuel is inherently better.

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Just now, Canopus said:

both shoot stuff out the back to make things go the other directions. I don't see how liquid fuel is inherently better.

Control. Look at all the Ares I problems. Yuck.

Solids are such an inelegant choice. In addition, the liquid side booster proposal (all these required since the core stage is such a bad idea) at least ups the mass to space substantially.

 

Unrelated to solids (except for the SLS connection)...

Here's an old read, but a good one. Pretty interesting in retrospect, it's from 2014 (Eric Berger, writing for the Houston Chronicle):

https://www.houstonchronicle.com/local/item/NASA-Adrift-Part-2-29938.php

 

 

In light of yesterday, this is pretty funny:

Quote

“Let’s be very honest,” Bolden said in an interview. “We don’t have a commercially available heavy-lift vehicle. The Falcon 9 Heavy may some day come about. It’s on the drawing board right now. SLS is real.”

 

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6 minutes ago, Canopus said:

both shoot stuff out the back to make things go the other directions. I don't see how liquid fuel is inherently better.

It’s more controllable. While it is possible to shut off solids and maybe even throttle them, liquids can be made to throttle, restart, and can be shut down faster, generally.

Another aspect is that solids release much more damaging gases than liquids generally do.

Liquids also have higher specific impulse or at least can. Also more energetic propellant from my understanding. Liquid stages can get more total impulse.

Solids are useful but I’d rather not use them on crew vehicles...

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Posted (edited)

@tater the Ares I issue stems from the long design of the vehicle does it not

9 minutes ago, tater said:

 

In light of yesterday, this is pretty funny:

 

Putting a single GEO sat into space, very impressive, sorry but Falcon Heavy will never be an SLS replacement, not by volume or mass capacity.

New Glenn, maybe Delta IV heavy, Vulcan or even Starship if that ever goes somewhere. but not FH.

Edited by Canopus

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5 minutes ago, Canopus said:

@tater the Ares I issue stems from the long design of the vehicle does it not

It was sitting Orion on top of a solid. Solids burn unreliably---they are a bumpy ride.

5 minutes ago, Canopus said:

Putting a single GEO sat into space, very impressive, sorry but Falcon Heavy will never be an SLS replacement, not by volume or mass capacity.

New Glenn, maybe Delta IV heavy, Vulcan or even Starship if that ever goes somewhere. but not FH.

The SLS Block 1 has had the mass capacity changed to 95t, apparently, but it somehow only remains capable of lofting the exact same Orion and upper stage to the exact same orbits it could do when the stated mass to LEO was 70t. Not sure how that works out. Maybe they calculate using a different nominal orbit to get 95t. Orion might have bloated a little, but it's 26t, it did not gain 25t.

At the time of that Bolden quote, SLS was 70t, FH was supposed to be 53t. We haven't seen the figures yet, but FH is very close to 70t at this point with block 5 (up from 63.8t). NASA just said that with ICPS on top, FH could actually do EM-1, it just can't be done quickly. Since EM-1 is basically all SLS can do... they look pretty darn similar in capability.

Volume?

SLS has zero volume advantage on FH. Block 1 has no fairing, and the one proposed for Block 1 is... 5m (same as the upper stage/Orion). If you want to talk about later versions of SLS, then it's every bit as real to talk about operational Starship or NG. If Blue Origin were to so much as release a render of New Armstrong, it would be every bit as real as SLS Block 2 assuming it used engines they have (or based on, like BE-4U).

Also, how is Delta IV Heavy even in the running? Mass is far lower, and it has a, wait for it, 5m fairing.

 

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Posted (edited)

A quick check with the F9 and DIVH payload guides shows that the F9 fairing is actually a larger interior diameter than DIVH (by all of 2.8cm, lol). It's substantially shorter than the tall version for DIVH, however (max F9 height inside taper is about where the DIVH fairing starts to taper). That said, the images published of SLS Block 1 with a fairing have a flush 5m fairing (exactly like DIVH), that looks to be about the same height as the DIVH tall one, so definitely more volume, albeit it has to be in length, not diameter.

Edited by tater

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Posted (edited)
21 minutes ago, tater said:

The SLS Block 1 has had the mass capacity changed to 95t, apparently, but it somehow only remains capable of lofting the exact same Orion and upper stage to the exact same orbits it could do when the stated mass to LEO was 70t. Not sure how that works out. Maybe they calculate using a different nominal orbit to get 95t. Orion might have bloated a little, but it's 26t, it did not gain 25t.

I think that's because the engineers knew the Block 1 had a much higher stated capacity than they made publicly available for a long time. Remember, that 70 mT figure was the Congressionally mandated minimum, and was really the figure you'd get by sticking with the 4-seg SRBs and non-stretched core. Once Block 0 - aka "Stumpy" - got thrown out in the early days of the SLS program, they were basically guaranteed to get a figure higher than that.

 

Edited by jadebenn

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FH could do EM-1, with the SM burn. 

from everything i have read, the 70 ton number for FH is not realistic, it doesn‘t seem to take structural and CoM issues into account.

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Just now, Canopus said:

FH could do EM-1, with the SM burn. 

from everything i have read, the 70 ton number for FH is not realistic, it doesn‘t seem to take structural and CoM issues into account.

If EM-1 was a flyby it could do it on a free-return trajectory. But I don't think EM-1 is a lunar flyby anymore.

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2 minutes ago, jadebenn said:

If EM-1 was a flyby it could do it on a free-return trajectory. But I don't think EM-1 is a lunar flyby anymore.

EM-1 never was. Em-2 was supposed to be manned flyby, but that has changed too.

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Posted (edited)
13 minutes ago, jadebenn said:

I think that's because the engineers knew the Block 1 had a much higher stated capacity than they made publicly available for a long time. Remember, that 70 mT figure was the Congressionally mandated minimum, and was really the figure you'd get by sticking with the 4-seg SRBs and non-stretched core. Once Block 0 - aka "Stumpy" - got thrown out in the early days of the SLS program, they were basically guaranteed to get a figure higher than that.

 

Still, Block 1 can only send Orion to a distant lunar orbit, as it has been stated for a while. Like FH, the payload mass to LEO is a sort of nonsensical figure, since you can't fit 65+ tons under the FH fairing, nor could you put 64t (edited*) under a (notional) SLS Block 1 fairing. All either number buys you is residual props, though it seems like in the case of SLS, those props are necessarily in the core. I suppose you launch elliptical, keeping perigee suborbital to dispose of the core.

Anyway, for FH, same thing, it's payload residuals. Bottom line is that there's no 5m payload that can use the full mass of EITHER to LEO.

13 minutes ago, Canopus said:

FH could do EM-1, with the SM burn. 

from everything i have read, the 70 ton number for FH is not realistic, it doesn‘t seem to take structural and CoM issues into account.

I don't disagree, but ditto 95t to LEO for SLS Block 1. It has a possible payload fairing that mimics DIVH. Unless they need a block of lead in LEO, it's not fitting under the fairing at 95t. (*actually, ICPS is part of that mass at just shy of 31t, making the mass allowed under the fairing to match FH almost exactly---and there isn't anything to put under the fairing that masses 64t for either vehicle).

SLS is a rocket to launch crew payloads. That requires Block 2, and the far larger fairing (flush 8.4m, or 10m). Crew payloads are mostly air. Props would make sense, but not with 1 launch a year, and a crew capsule on top (since that's EUS, which also isn't good enough).

8 minutes ago, Canopus said:

EM-1 never was. Em-2 was supposed to be manned flyby, but that has changed too.

Yeah, these all change around so much it's confusing. I was used to them being the same for a while. Course I was used to ARM before that, lol.

Edited by tater

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58 minutes ago, Canopus said:

Putting a single GEO sat into space, very impressive

*one more than SLS

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Just now, sh1pman said:

*one more than SLS

The point is that SLS is not supposed to put 5 ton sats into GEO. FH is. It is definitely not designed to put superheavy payloads into LEO.

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Posted (edited)
33 minutes ago, Canopus said:

FH could do EM-1, with the SM burn. 

from everything i have read, the 70 ton number for FH is not realistic, it doesn‘t seem to take structural and CoM issues into account.

And the small size of the fairing. Eventually heavier payloads will need more space than the pitiful size of the FH fairing unless SpaceX is lofting literal depleted uranium and osmium into space. SLS may not even be remotely efficient but the larger fairing size does offer a range of functionality the FH cannot.

Not considering Vulcan/NG/BFR as they aren't around yet. By the time they are, B2 of SLS should be in it's final round of testing and nearing the end of SLS' run as NASA begins to closely monitor the other groups so NASA can utilize their LVs instead of the costly SLS. But until SLS flies, that's all they see for BEO.

For LEO and GEO, SpaceX and ULA rule those regions of space. NASA has no interest.

----------------------------------------------------------------------------------------------------------------------

Also I think this would be appropriate for this thread right about now with Boeing's ongoing issues-

image0.jpg

Edited by ZooNamedGames

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30 minutes ago, Canopus said:

The point is that SLS is not supposed to put 5 ton sats into GEO. FH is. It is definitely not designed to put superheavy payloads into LEO.

Actually, this is entirely untrue. SLS is for BLEO, pretty much exclusively. This is certainly true of Block 1 and Block 1b as they either send space probes (not a thing, since no one can make a probe expensive enough to justify it), or Orion, or in the case of 1b, Orion plus a small Gateway module (~10 tonnes). Block 2 might possibly be useful for huge payloads to LEO, but the same rule tends to apply that we have with FH, etc, that the bulk of the mass to LEO is upper stage propellant. Even with the 10m fairing on Block 2, a fair chunk of that value to LEO is in fact the EUS mass.EUS has a spec of propellant mass not to exceed 129 tonnes. Given that the current spec on SLS Block 2 is 130 tonnes to LEO, I'm not sure what this buys you.

Wiki (using the current 95, 105, and 130 t values for B1, B1b, and B2) has the TLI mass of B1b as 37t. Assume EUS is common between them (no where near 129t), then to TLI you get Orion +11t, or plain cargo exactly the same mass, 37t.

Any payload to LEO needs to dump the EUS, but also needs to have an engine, since the final burn has to come from ICPS/EUS/payload (so the core can dispose of itself, perigee has to be low).

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Posted (edited)

@tater Sorry i wasn‘t trying to imply SLS is meant for LEO, just that FH is supposed to put Satellites into geosynchronous orbits not launch heavy payloads. 

Could have worded that a little better.

Edited by Canopus

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Posted (edited)
43 minutes ago, ZooNamedGames said:

Not considering Vulcan/NG/BFR as they aren't around yet.

Neither is SLS, though it's farther along than all 3 you mention.

Quote

By the time they are, B2 of SLS should be in it's final round of testing

Where does this come from? Currently even Block 1b is sorta out there in the void, and Block 2 requires new boosters that don't exist.

Vulcan is planned (could slip, obviously) to fly Spring 2021. The only way SLS Block 1 even beats Vulcan to flight is killing the Green Run test, else it's a similar time frame. ULA/BO have said they are unsure if Vulcan of NG will fly BE-4 first, so NG is flying in a similar timeframe to the very first SLS flight. BFR is testing flight article engines, and doing software dev on landing soon (Hopper). It;s not ready parts set to be assembled (SLS), but it's not a paper rocket, either. It could totally fly in the realm of EM-1 to EM-2 (the latter is set 2 years AFTER EM-1, whenever that happens to be, else maybe 2022, if they somehow stay on schedule with EM-1 behind).

Block 1b isn't even penciled in until EM-3 (2024). Block 2 not for 10 years.

Quote

and nearing the end of SLS' run as NASA begins to closely monitor the other groups so NASA can utilize their LVs instead of the costly SLS. But until SLS flies, that's all they see for BEO.

True, from when they started, but again, the whole thing was supposed to cost 9 billion. By a crew flight it's more like 40.

7 minutes ago, Canopus said:

@tater Sorry i wasn‘t trying to imply SLS is meant for LEO, just that FH is supposed to put Satellites into geosynchronous orbits not launch heavy payloads. 

Could have worded that a little better.

I was quoting mostly for the point that both sides (SLS/FH) tend to forget, that mass to LEO is sort of meaningless when payloads are not usually mass limited to LEO. It's sort of a raw benchmark to roughly compare.

Edited by tater

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1 minute ago, tater said:

Neither is SLS, though it's farther along than all 3 you mention.

Where does this come from? Currently even Block 1b is sorta out there in the void, and Block 2 requires new boosters that don't exist.

Vulcan is planned (could slip, obviously) to fly Spring 2021. The only was SLS Block 1 even beats Vulcan to flight is killing the Green Run test, else it's a similar time frame. ULA/BO have said they are unsure if Vulcan of NG will fly BE-4 first, so NG is flying in a similar timeframe to the very first SLS flight. BFR is testing flight article engines, and doing software dev on landing soon (Hopper). It;s not ready parts set to be assembled (SLS), but it's not a paper rocket, either. It could totally fly in the realm of EM-1 to EM-2 (the latter is set 2 years AFTER EM-1, whenever that happens to be, else maybe 2022, if they somehow stay on schedule with EM-1 behind).

True, from when they started, but again, the whole thing was supposed to cost 9 billion. By a crew flight it's more like 40.

That’s assuming everything goes to plan for all 3 rockets. Vulcan is just a metal sheet right now. NG is just paper for the time being. BFR has a small scale tin foil model that’s basically doing short test fire equalivants to NASA’s RS-25. The orbital variant is still being made and likely won’t see actual flight until after EM-1. If all 3 companies keep to schedule, there’s no financial struggles, and no roadblocks in testing, no failures, no miscalculations, and every milestone is hit on time, then yes. They will fly before B2 is even partly ready. But unless they hit that level of perfection and efficiency in operation (whether human or mechanical), B2 will have new boosters, New first stage fuel tank, EUS (by someone other than Boeing).

With flights, SLS operations will accelerate as we gain experience using SLS in flight environments and we gain more pressure to develop B2 as it’s no longer “5 missions away” but instead the next mission. Besides NASA won’t have a choice with the new boosters as ATK will run out of the old and they’ll have to upgrade. 

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3 minutes ago, ZooNamedGames said:

BFR has a small scale tin foil model that’s basically doing short test fire equalivants to NASA’s RS-25.

The RS-25s are just being fired in a test stand. The "small scale tin foil model", which is the same diameter as the full sized Starship, is actually moving off the ground, and will most likely fly untethered before the end of the month.

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42 minutes ago, Barzon Kerman said:

The RS-25s are just being fired in a test stand. The "small scale tin foil model", which is the same diameter as the full sized Starship, is actually moving off the ground, and will most likely fly untethered before the end of the month.

Until it’s untethered, it’s a test stand. Moreover the hopper isn’t space worthy. The EM-1 vehicle is. 

Your comparing the Space Shuttle Enterprise to the Buran. 

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44 minutes ago, ZooNamedGames said:

That’s assuming everything goes to plan for all 3 rockets.

All 4 rockets.

EM-1 is 2021 right now, short of cutting a corner to move it back into 2020. Unsure where EM-2 stands, maybe it stays 2022 (though as a block 1, something that was never supposed to happen). Once they pull the trigger on Block 1b+, then there is a 33 month delay to ready the MLP/VAB, regardless (unless they were lying about that timing before to cover other schedule issues).

Literally any problem with any element of SLS/Orion will result in further schedule slips, they have no slop left.

I agree the other rockets have all the same problems, and they will likely slip as well.

 

44 minutes ago, ZooNamedGames said:

Vulcan is just a metal sheet right now.

Bent into tank shapes, and assembled the same way their factory builds other rockets.

44 minutes ago, ZooNamedGames said:

NG is just paper for the time being.

We don't know that much about what's going inside at BO, they are kinda close mouthed. That said, they have actual customers. Customers who can buy launches from their competitors. They have a motivation to be on time (unlike SLS contractors, they don't get paid more for being late).

44 minutes ago, ZooNamedGames said:

BFR has a small scale tin foil model that’s basically doing short test fire equalivants to NASA’s RS-25. The orbital variant is still being made and likely won’t see actual flight until after EM-1.

EM-1 is at the very best happening in 1.5 years. Probably 2. I have no idea if an orbital-capable Starship will fly in that timeframe, but neither do you. I agree that it might not fly, but I can't say with any certainty one way or another.

 

44 minutes ago, ZooNamedGames said:

If all 3 companies keep to schedule, there’s no financial struggles, and no roadblocks in testing, no failures, no miscalculations, and every milestone is hit on time, then yes. They will fly before B2 is even partly ready. But unless they hit that level of perfection and efficiency in operation (whether human or mechanical), B2 will have new boosters, New first stage fuel tank, EUS (by someone other than Boeing).

B2 is not supposed to fly until 2029. In the short term, I'm open to all 4 failing one way or another. In the longer term I'm willing to be more certain.

There is near zero probability that ULA is not flying Vulcan by then.

There is near zero probability that NG will not be flying by then.

There is near zero probability SpaceX is not flying some next-generation rocket by then (they sort of have to to stay around vs BO).

 

44 minutes ago, ZooNamedGames said:

With flights, SLS operations will accelerate as we gain experience using SLS in flight environments and we gain more pressure to develop B2 as it’s no longer “5 missions away” but instead the next mission. Besides NASA won’t have a choice with the new boosters as ATK will run out of the old and they’ll have to upgrade. 

No, operations are set to up to 2/year later on. It's a budget constraint.

8 minutes ago, ZooNamedGames said:

Until it’s untethered, it’s a test stand. Moreover the hopper isn’t space worthy. The EM-1 vehicle is. 

Your comparing the Space Shuttle Enterprise to the Buran. 

Neither analogy is very good. A test stand is quite different from something that will fly. The forces on it, for example. A test stand gets perfect propellant delivery, the hopper, even tethered, has forces on it the second it fires.

The hopper is really to test getting it to work on a real (but cheap) vehicle, then software for control and landing ops.

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